Measles is a highly contagious respiratory disease caused by a virus that is spread by direct contact with nasal or throat secretions of infected people. People first develop a fever, then often a cough, runny nose and watery eyes, followed by an appearance of a rash. People are considered infectious four days before to four days after the appearance of the rash.

Symptoms include a fever, rash, cough, conjunctivitis or a runny nose. Symptoms usually appear 10-12 days after exposure but may appear as early as 7 days and as late as 21 days after exposure.